Modern wind turbine rotor blades are built from fiber-reinforced plastics. A rotor blade typically comprises an airfoil having a rounded leading edge and a sharp trailing edge. The rotor blade is connected with its blade root to the hub of the wind turbine. The rotor blade is connected to a blade bearing by an adjustment device that is configured to adjust a pitch angle of the rotor blade. The blade bearing is connected to the hub and allows a rotational movement of the rotor blade relative to the hub. The adjustment device comprises an actuator generating an adjustment force.